JP-A-H08-132831 discloses an apparatus for determining a tire related conditions such as air pressure in a tire, an abrasion amount of a tire, and vibrating modes of a tire, e.g., a standing wave mode based on a tire-uniformity component. The tire-uniformity component is a variable which may be indicated by a fluctuation on rotation speed of a wheel during a rotation of the wheel. The tire-uniformity component can be obtained by processing a signal indicative of rotation speed of a wheel.
One embodiment of a practical application of the tire-uniformity components and a method for calculating the tire-uniformity components is described in JP-A-H08-132831, which is incorporated herein by reference. Additionally, a brief description of the tire-uniformity components is provided below.